G Lazaro
International Baccalaureate Chemistry Tick List
Topic 14: Bonding
14.1 Shapes of Molecules and Ions
14.1.1 State and predict the shape and bond angles using the
VSEPR theory for 5 and 6- negatives charge centres
The shape of the molecules/ions and bond angles, if all pairs
of electrons are shared, and the shape of the molecules/ions
if one or more lone pairs surround the central atom, should
be considered. Examples such as PCl5, SF6 and XeF4 can be
used.
14.2 Hybridisation
14.2.1 Describe sigma and pi bonds
Treatment should be limited to
sigma bonds - electron distribution has axial symmetry around
the axis joing the two nucleii
pi bonds resulting from the combination of parallel p orbitals
double bonds formed by a sigma and a pi bond
triple bonds fommed by a sigma and twp pi bonds
14.2.2 State and explain the meaning of the term
hybridisation
Hybridisation should be explained in terms of the mixing of
atomic orbitals to form new orbitals for bonding. Students
should consider sp, sp2 and sp3 hybridisation, and the shapes
and orientation of these orbitals
14.2.3 Discuss the relationships between Lewis structures,
molecular shapes and the types of hybridisation (sp, sp2 annd
sp3).
Using examples from inorganic as well as organic chemistry,
students should write the Lewis structure, deduce the shape
of the molecule and recognise the type of hybridisation
14.3 Delocalisation of Electrons
14.3.1 State what is meant by the delocalisation of pi
electrons and explain how this can account for the structures
of some substances.
Examples such as NO3-1, NO2-1, CO32-, O3, RCOO-1 and
benzene can be used. These could also be dealt with through
the resonance approach
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G Lazaro
International Baccalaureate Chemistry Tick List
14.4 Structures of Allotropes of Carbon
14.4.1 Describe and explain the structures and properties of
diamond, graphite and fullerene
Students should recognise the type of hybridisation present in
each allotrope and the delocalisation of electrons in graphite
and fullerene.
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